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How Do I Troubleshoot The Trailer Wiring Of My 2022 Toyota Highlander  


I am having issues with the trailer wiring on my 2022 Toyota Highlander. None of my trailer lights work for any functions, I am not sure where the problem is located. Is it my harness? What can I do to fix it?


Expert Reply:

In order to troubleshoot your 2022 Toyota Highlander wiring installation you will need some tools to assist you. You will need a 12V circuit tester. I recommend the Cordless Circuit Tester, part # PTW2979. In addition, you will also need basic wiring tools, electrical tape, a wire stripper, dielectric grease, and wiring fasteners. Troubleshooting your trailer wiring can be very intensive.

This can be caused by a number of issues. If you have a plug in harness, it may be for models with a factory tow package and your vehicle does not have tow package installed, or you have a fuse or relay that is blown or missing. Your harness may not have a connection to the ground, it could be overloaded. You are going to have to do a step by step diagnosis and eliminate these potential causes one by one to find the specific issue that is causing your problem.

If you do not have a factory tow package this would just require that you replace the existing harness for one that is for vehicles that do not have the factory tow package. The T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector, part # TK99FR, would work with your 2022 Toyota Highlander. If this will not address your problem you will have to test your system, piece by piece.

I have included a weblink below that will go through each of the steps and a second weblink discussing 4-way connector to direct you. I have also included a product description link, an installation video link, and a video review link below.

expert reply by:
Mark Smith

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